The commercially used inkjet printer often uses ink cartridge with capacity up to 4000 ml. To avoid occupying too much space when the ink cartridge is installed in the printer, the ink cartridge is usually designed as a long shape with the ratio of length vs. width as high as six to one. A collapsible ink bag is included inside this type of ink cartridge, and is responsible for supplying a large amount of ink continuously.
To ensure that the user is alerted of the time of running output ink and to change the cartridge, one side of the ink bag is partially glued to the inner bottom of the cartridge, and the other side of the ink bag is disposed with a trigger based on the remaining ink amount. The trigger can move towards a specific direction as the amount of ink reduces and the ink bag shrinks or flattens. The specific direction is towards the side glued to the bottom of the cartridge. When the trigger touches a sensor in the printer, the printer will issue an alert for replacing the cartridge to inform the user. Because of the trigger, the bottom of the ink bag must also be attached to the bottom of the cartridge, which leads to difficulty in replacing the ink bag. Hence, the commercial large-size ink cartridge is often a disposable product. The entire cartridge must be replaced when the ink is exhausted, instead of simply replacing the ink bag. As a result, the purchase cost is higher and the discarded cartridge cause extra environmental burden and resource waste. Thus, it is imperative to devise a solution to the above shortcomings of the known technique.